This page is worth opening before you soak anything — it is deliberately short, because it gets read at the moment everything is already laid out on the table. The per-metal detail lives in its own guides: copper, silver, iron, preservation.
Before you begin — five minutes that save the object
These five minutes are spent once, before the object goes anywhere near water, a brush or a solution. Until every line is closed, cleaning does not begin: the first 24 hours after a find decide more than whatever method you pick afterwards.
| Check | Done? |
|---|---|
| Reference photos with a scale and an ID exist | ☐ |
| Date, private location reference and the source of the find hypothesis are recorded | ☐ |
| The material is stated with a confidence level, not from colour alone | ☐ |
| Stop signals checked: organics, glass, plating or gilding, hallmark, active corrosion, hazardous context | ☐ |
| The purpose of the intervention is clear, and so is the criterion for stopping | ☐ |
| The object is separated from the others and has its own record card | ☐ |
| It is clear where and how every material and action used will be logged | ☐ |
A stop signal on the fourth line is not a reason to look for a gentler method. It is a reason to stop, leave the object as it is and show it to a conservator: damp organics, glass, enamel, thin plating and loose active corrosion do not forgive a "trial" clean.
Eight expensive mistakes
All of them happen constantly, and all of them are irreversible.
- Polishing compound on silver. Fast, shiny, and the collector value is gone.
- Dry felt and coarse abrasives. A web of scratches that shows under any light.
- Open chemistry next to the collection. The fumes will spoil coins you never took off the shelf.
- Several metals in one bath. Galvanic corrosion doesn't ask permission.
- Leaving it too long in acid. Soft pink metal where a coin used to be.
- A scalpel on silver. Silver is soft; the relief goes with one wrong movement.
- Dry fiberglass. It only works in water or a soapy bath.
- Wax over active disease. That isn't treatment, that's a lid.
Before you start
- Metal identified — or the softest protocol deliberately chosen instead.
- The piece is definitely not a rarity, and cleaning is a considered decision.
- A "before" photo exists (and an AI preview if you want to see options risk-free).
- Gloves, ventilation and distilled water to hand.
- The rest of the collection is out of the work area.
- You know how it ends: drying, then wax or oil.
What you're risking
| Product | Typical risk |
|---|---|
| Laundry soap | Essentially none. This is the baseline |
| Citric acid | Silver goes matte if left too long |
| Sesquicarbonate | Needs the copper spots watched |
| Electrolysis | Reversed polarity, over-etched iron |
| Abrasives | Scratches, permanently |
After cleaning
There is no general "rinse and dry" rule. Water, salts, glass, damp organics, porous materials and composite objects each call for a different decision. If you cannot explain why this object needs contact with water and how the result will be controlled, contact with water does not begin.
What "justifying the water" means in practice, and why dissolved salts are more dangerous than visible dirt, is covered in Water, salts and hydrolysis. After that, the order is:
- A distilled rinse — only if water contact was part of the plan and the object tolerates it.
- A full dry, all the way through rather than by eye: moisture under a barrier works against you.
- A thin barrier — and only onto a dry, stable surface.
- Date, product and purpose into the conservation log, the same day.
- A look at it again a few weeks later, and from there follow the monitoring after conservation schedule rather than your memory.
And the rule that covers everything else: if you're unsure, don't clean. A dirty readable coin always beats a shiny dead one.
External orientation
If the checklist leaves doubts, compare your plan with Canadian Conservation Institute — Metals. The rule is simple: a step you cannot explain is a step to skip.